Grinding machine

ABSTRACT

A grinding machine for grinding the upper surface of a workpiece having a reciprocable table for the workpiece and a driven grinding wheel pivotally supported above said table and having a horizontal axis with the axis of pivoting of said grinding wheel extending through the center of said grinding wheel axis and also located between the outer sides of said grinding wheel while said grinding wheel is also capable of vertical movement relative to said table.

T r" M [1 1 [111 3,7,M2 Soderstrom Aug. 7, T973 1 GRINDING MACHIINE 3,039,236 6/1962 Thiel et al 51/99 ,954 D' 5| 9 [76] Inventor: Lars Soderstrom, Centro-Maskm l 3 100 M963 Lena I 2 R x Goteborg AB, Box 47052, 8 400 51 Goteborg, Sweden Primary Examiner-Othell M. Simpson [22] Filed: May 19 Attorney-L1nton & Linton [2]] Appl. No.: 144,900

[57] ABSTRACT [30] Foreign Application Prim-y A grinding machine for grinding the upper surface of May 12, 1971 Sweden 6l55/7l a workpiece having a reciprocable table for he work piece and a driven grinding wheel pivotally supported [52] U.S. Cl. 51/34 M, 51/45, 51/99 above said table and having a horizontal axis with the [51] lint. Cl B24! 7/00, B24b 9/00 axis of ivotin of said rindin wheel extendin Id of Search 51/45 34 47 99 p g g g [58] Fm through the center of said grinding wheel axis and also 51/92 R located between the outer sides of said grinding wheel while said grinding wheel is also capable of vertical [56] References (med movement relative to said table.

UNITED STATES PATENTS 2,982,056 5/1961 Edquist .TQ 51/45 4 Claims, 4 Drawing Figures PATENIED 3.750.342

W I 4 "m.

FIG. I

INVENTOR. LRRS SODERSTROM HTTORNYS PATENIED AUB 7:915

SHEET 2 OF 4 INVENTOR. LARS SODERSTROM BY ATTORNEY PATENTEDAUB H915 3,750,342

SHEET 3 BF 4 FIG. 3

' INVENTOR. ILARS SODERSTROM BY M M Z ATTOEIYEYS PATENIEDAUE 1W 7 3.750.342

' SHEET U [1F 4 FIG. 4

IN V EN TOR.

LAB/i5 SODERSTROM 'ATTO RrvEYs GRINDING MACHINE The present invention relates to grinding machines for grinding the upper surface of a blank or billet or a similar workpiece thereof, and comprises means for the support of the workpiece, means for the rotatable carrying of the grinding wheel on a horizontal shaft, means for driving the grinding wheel shaft and means for the relative movement of the carrying means for the workpiece and the carrying means for the grinding wheel in a horizontal plane in two directions perpendicular to each other, preferably for reciprocating motion, and in a vertical plane, preferably for the feeding of the grinding wheel towards the grinding surface of the workpiece, the means for carrying the grinding wheel comprising a pivoting assembly arranged to pivot the shaft of the grinding wheel in a horizontal plane between two positions, in the one holding the shaft of the grinding wheel in parallel alignment to one of the directions of movement in the horizontal plane, and in the other holding the shaft in an oblique angle of preferably 45 thereto in the same horizontal plane.

In grinding machines of this type of the prior art the workpiece rests on a table moving in reciprocating motion in one of the directions of movements mentioned. The grinding wheel, which is placed above the workpiece, can reciprocate in a horizontal plane in the other one of he,di sqt ns tmysmsnt mentiqesdsie, in a direction deviating 90 from the direction of movement of the table. In order to obtain this motion a slide is provided, which on account of practical considerations of the utilization of space is located at the side of the aforementioned table.

During the grinding operation the grinding wheel rotating around a horizontal shaft shall be able to occupy such a position that its shaft is directed in the same direction as the direction of the table movement, but also in a direction forming an angle of about 45 thereto as seen in a horizontal plane. Thereby a larger grinding surface and consequnetly a better surface finish of the ground surface is obtained than by aligning the shaft of the grinding wheel in the direction ofthe movementof the table. In the latter case a greater removal of material is on the other hand obtained in the grinding operation. The two setting positions for the grinding wheel therefore are complementary to each other in so far as a grindingwheel set at an oblique angle is preferable, when the workpiece has a fairly smooth surface, while the setting with the shaft parallel to the direction of the table movement is used, when rough portions shall be removed by the grinding operation. It is thus desirable to possibly switch the setting from one of said two positions to the other one.

Because thereof billetgrinding machines usually are provided with means for the pivoting of the grinding wheel between said two positions. In this case the pivoting axis is placed near to said slide located at the side of the table. This means that the grinding wheel, when pivoting, will move along the peripherical path of a circle. Thereby also the working range of the grinding wheel is displaced which makesit necessary to adjust the ranges of relative movement between the workpiece and the grinding wheel. In billet grinding machines of the prior art the pivoting of the grinding wheel between said two positions thus involves a complicated resetting operation.

The object of the present invention is to provide devices by means of which said change of the alignment of the grinding wheel can be undertaken without the necessity of any other reset operations of the machine.

It is another object of the invention to provide devices with reliable and practical elements, which make said alignment change possible.

It is further an object of the invention to provide de vices, which make it possible that the alignment change device can be provided with power means.

The objects mentioned above are provided by means of a device, which is characterized by supporting means for the pivotably mounted part, the pivot axis of which extending through the center of the shaft of the grinding wheel and located between its outer axial sides when the grinding wheel is mounted on its shaft.

In the accompanying drawings and in the description below an embodiment of the invention is explained. In the drawings FIG. l is a side elevational view of a grinding machine according to the invention, FIG. 2 is a portion of the machine illustrated in FIG. 1 comprising the grinding wheel with connected parts on an enlarged scale compared to FIG. 1, FIG. 3 is a view on a still further enlarged scale showing the position of the machine according to FIG. 2 as seen in the direction of the arrow III in said drawing, and FIG. 4 is a cross sectional view along the line IV-IV of FIG. 2 illustrating the upper pivot for the grinding wheel.

In FIG. 1 two frame structures are indicated with l and 2 respectively, both being placed on a floor plane 3. The frame 1 supports a slide 4, which is supporting a table 5. On this table a workpiece 6 is placed, whose upper surface is to be machined by means of a grinding wheel 7. The table 5 is movable along the slide 4 in a direction, which is perpendicaular to the plane of the paper sheet. The means for this movement are made in such a manner that the table performs a reciprocating motion between two adjustable end positions.

At the top side of the frame 2 an additional slide is provided, but not shown in the drawing. This slide, located in the direction represented by a surface 8, supports movably an upper part 9. For the movement of the .upper part 9 there are provided means arranged to effect a reciprocating movement at a right angle to the direction of movement of the table 5 which movement can be obtained between two end positions.

At the side of the upper part 9 facing the table 5, a carriage K0 is mounted and provided for a vertical direction of movement, i.e. in a plane coinciding with the plane lll. In the carriage 10 a pivotable part 12 is supported by means of bearings 13 and 14. This pivotable part 12 carries the grinding wheel 7 provided with a dust protection casing IS, an electric motor 16, and a belt drive 17.

By means of the movement in the slide 4 and the slide located in the plane 8, which movements both can take place in a horizontal plane with directions deviating from each other at an angle of 90, a relative movement between the workpiece 6 and the grinding wheel 7 is upper part 9 (IFIG. ll). Two arms are mounted on the mounting plate 18, an upper arm 19 and a lower arm 20. They are supported by brackets. At their extreme ends the arms 19, carry bearings 13 and 14 respectively.

The pivoted part 12 is carried by the bearings 13 and 14. This part comprises a supporting plate 21 with arms 22, 23, which at their extreme ends are carried by the bearings 13 and 14 mentioned above. The motor 16 is mounted on the supporting plate 21 by means of a plate 24, which can be displaced along the supporting plate 21 for the tensioning of the belt drive 17. The shaft of the grinding wheel (not shown) which axis is indicated by b, is rotatably mountd at the lower portion of the supporting plate. The grinding wheel 7 is mounted on this shaft in conventional manner.

The parts now mentioned comprised in the pivotally part 12 according to FIG. I are also illustrated in FIG. 3 in which they are seen in the direction of the arrow III of FIG. 2.

However, in FIG. 2 only an hydraulic power cylinder 25 is shown above the bracket 29 and attached to the plate 18. A double action piston in the cylinder acts upon the supporting plate 21 by means of a piston rod 26, the outer end of which is connected to a bearing 27 on said plate 21. By supplying pressure liquid ahead of or behind the piston, the supporting plate 21 and consequently the parts mounted thereon can be pivoted between two positions determined by stop elements now shown. In one of these positions, illustrated in FIGS. 1 3, the center axis b of the grinding wheel shaft is parallel to the direction of the table movement. The relative position between the workpiece and the grinding wheel at the other position of the pivotable part is not shown but the angle of pivoting should perferably as mentioned above be about 45, which thus corresponds to the angle between the center axis b of the grinding wheel shaft and the direction of movement of the table in the other position. The contact surface in this position is as mentioned larger than in the first position.

As is clearly evident from FIGS. 2 and 3 the pivoting movement is taking place around a vertical axis a which crosses the center axis b of the grinding wheel shaft and located in an axial plane c between the two outer sides of the grinding wheel. The pivoting axis a is thus located in the intersection point between the axis b of the grinding wheel and the axial plane c.

A pivoting movement of the grinding wheel consequently does not cause any sidewise displacement whatsoever of the grinding wheel 7, only a pivoting of the same. Neither is the contact surface between the workpiece and the grinding wheel, i.e. the grinding zone, displaced, it is only modified as to shape and size. The fact that no displacement of the grinding zone takes place is as already mentioned a distinct advantage for the easy setting and handling of the machine. The table movement d as well as the transversal movement e, the latter one caused by the upper part 9, FIG. 1, is suitably adjusted in such a manner that the movement of the grinding wheel over the workpiece will cover the desired grinding surface but nothing more, as by this arrangement the shortest machining time is obtained. A displacement of the grinding zone as by machines of the prior art would therefore involve the necessity of adjusting the respective range of movement, usually limited by adjustable end stops, in order to secure a continued coverage of the total surface of the workpiece by the movements of the grinding wheel relative to the same.

At the pivoting movement of the grinding wheel round position axis a also the driving motor 16 of the grinding wheel has to be pivoted in order to avoid the introduction of complicated power transmission means. The pivoting part 12, FIG. 1, thus comprises several heavy and at the same time vibration causing elements. In known grinding machines the pivoting axis, as mentioned, is located in a position within the extension of the upper part, FIG. I. Said part permits the possibility of incorporating strong and well supported bearings, while with the pivoting axis a placed according to the present invention, the bearings have to be made in a positio far out and with very little space requirement. Yet in order to secure absence of play and vibrations a bearing assembly according to FIG. 4 can be used.

This bearing assembly, which is sectioned along the line IV-IV in FIG. 2 comprises a bearing housing 28 attached to the arm 19. In this housing a bearing seat 29 is clamped in a position between a bottom 30 connected to the bearing housing 28 by means of screws 31, and an upper part 32, connected to the bearing housing 28 by means of screws 33. The upper part 32 at its top is provided with a lid 34 rigidly mounted thereon, a screwtap 35 being threaded into said lid. The screw tap 35 forms part of a spindle, the other parts of which are a flange 36 and a shaft 37. The screw tap 35 at its extreme end terminates in a key grip 38 and is locked against involuntary turning in the lid by means of a locking nut.

A pivot shaft is rigidly mounted in the arm 22. The shaft pivot comprises a bearing part 39 with a conical bearing surface cooperating with the likewise conical bearing surface of the bearing seat 29, and a cylindrical part and moreover a pin shaft portion 40 provided with a key-way and terminating in a threaded gudgeon 41. When the shaft pivot is mounted in the arm 22 it is secured against turning by means of a key 42 for which key-ways are provided in the pivot shaft and the arm. Tightening of the pivot shaft is made by means of a nut 43, which is threaded onto the gudgeon 41 and via an intermediate washer and a lock washer is pressing against the arm 22. A seal ring 46 is inserted in the bottom 30 and serves the purpose of preventing dust from penetrating into the bearing surfaces and leakage of lubricant out from the bearing housing. In order to guide the shaft 37 there is a hole 44 in the pivot shaft 39.

In order to prevent play and vibration, the bearing surfaces are pressed against each other by means of cup springs 45. These bear on the one hand against the pivot shaft 39 via washers and on the other hand against the bearing housing via the intermediate flange 36, the screw tap 35, the lid 34, and the upper part 32. Via the bearing housing 28 and the bottom 30 the force is transmitted to the bearing seat 29 and tends to press the bearing surfaces together. The spring force is adjustable by screwing the screwtap 35 up and down in the lid 34 thereby displacing the flange 36 increasing and decreasing respectively the space for the cup springs 45.

Usually it is sufficient if one of the bearings, suitably the upper one, see at 13 in FIG. 1, is of the decided type, free from play. The lower bearing, see at 14 in FIG. 1, can therefore be of conventional type, which is also shown in the figures. The illustrated dividing up in two separate bearings instead of using bearings on a through shaft is chosen in the first place for making it possible to locate the electric motor in such a manner that the most even possible distribution of weight around the geometrical axis a is obtained. Thereby the smallest possible sidewise acting forces and consequently the least stress on the construction is obtained.

As is evident from the above, essential improvements of the functioning have been obtained by locating the pivoting axis a to the center of the grinding wheel. it has also been clear that this location has been made possible by providing special means therefore, viz. the incorporation of the pivoting part ill in the design and the arrangement of its parts as well as the design of the bearing according to FIG. 41.

By the power unit 25 additional means has been provided for the pivoting movement of the grinding wheel without manual intervention, something which would not have been possible if, as in known grinding machines of this type, a simultaneous pivoting movement would have involved the necessity of resetting of the positions for the relative movement between the grinding wheel and the workpiece.

The embodiment described and illustrated is chosen as an example only and can be varied as to its details within the scope of the following claims without departing from the fundamental idea of the invention. The device according to the invention can also be used in other types of grinding machines than the one described and illustrated.

I claim:

1. A grinding machine for grinding the upper surface of a workpiece comprising a grinding wheel, means for supporting the workpiece, means for rotatably supporting said grinding wheel with its axis extending horizontally, means for driving said grinding wheel, means for providing relative movement of said supporting means for the workpiece and said carrying means for said grinding wheel in a horizontal plane in two directions perpendicular to each other and in a vertical plane for the feeding of said grinding wheel towards the grinding surface of the workpiece, said means for carrying said grinding wheel comprising a pivoting assembly arranged to pivot the axis of said grinding wheel in a horizontal plane between two positions, in one position holding the axis of said grinding wheel in parallel alignment to one of the directions of movement in the horizontal plane, and in the other position holding axis of said grinding wheel in an oblique angle of preferably 45 thereto in the same horizontal plane, said pivoting assembly having pivotal supporting means for said grinding wheel with the pivot axis of said pivoted supporting means extending through the center of the axis of said grinding wheel and located between the outer axial sides of said grinding wheel.

2. A grinding machine according to claim 1 wherein said pivotal supporting means has a pivotable part, a drive for said grinding wheel mounted on said pivotal part.

3. A grinding machine according to claim 2 wherein said pivotable part is journalled at least in one of said pivotal supporting means comprising a pivot shaft and a bearing seat, the cooperating surface of said pivot shaft and said seat having a conical shape, resilient elements arranged to press said conical bearing surface of the pivot against the conical bearing surface of said bearing seat.

- d. A grinding machine according to claim ll including power means provided for pivoting of said pivotal supporting means. 

1. A grinding machine for grinding the upper surface of a workpiece comprising a grinding wheel, means for supporting the workpiece, means for rotatably supporting said grinding wheel with its axis extending horizontally, means for driving said grinding wheel, means for providing relative movement of said supporting means for the workpiece and said carrying means for said grinding wheel in a horizontal plane in two directions perpendicular to each other and in a vertical plane for the feeding of said grinding wheel towards the grinding surface of the workpiece, said means for carrying said grinding wheel comprising a pivoting assembly arranged to pivot the axis of said grinding wheel in a horizontal plane between two positions, in one position holding the axis of said grinding wheel in parallel alignment to one of the directions of movement in the horizontal plane, and in the other position holding axis of said grinding wheel in an oblique angle of preferably 45* thereto in the same horizontal plane, said pivoting assembly having pivotal supporting means for said grinding wheel with the pivot axis of said pivoted supporting means extending through the center of the axis of said grinding wheel and located between the outer axial sides of said grinding wheel.
 2. A grinding machine according to claim 1 wherein said pivotal supporting means has a pivotable part, a drive for said grinding wheel mounted on said pivotal part.
 3. A grinding machine according to claim 2 wherein said pivotable part is journalled at least in one of said pivotal supporting means comprising a pivot shaft and a bearing seat, the cooperating surface of said pivot shaft and said seat having a conical shape, resilient elements arranged to press said conical bearing surface of the pivot against the conical bearing surface of said bearing seat.
 4. A grinding machine according to claim 1 including power means provided for pivoting of said pivotal supporting means. 